A cylinder has inner and outer radii of #12 cm# and #15 cm#, respectively, and a mass of #4 kg#. If the cylinder's frequency of rotation about its center changes from #5 Hz# to #2 Hz#, by how much does its angular momentum change?

1 Answer
Aug 21, 2017

Answer:

The change in angular momentum is #=1.39kgm^2s^-1#

Explanation:

The angular momentum is #L=Iomega#

where #I# is the moment of inertia

The mass of the cylinder is #m=4kg#

The radii of the cylinder are #r_1=0.12m# and #r_2=0.15m#

For the cylinder, #I=m(r_1^2+r_2^2)/2#

So, #I=4*(0.12^2+0.15^2)/2=0.0738kgm^2#

The change in angular velocity is

#Delta omega=Deltaf*2pi=(5-2)*2pi=6pirads^-1#

The change in angular momentum is

#DeltaL=I Delta omega=0.0738*6pi=1.39kgm^2s^-1#